CN114279312B - High-sensitivity braided strain sensor and preparation method thereof - Google Patents

Abstract

The invention discloses a high-sensitivity braided strain sensor, which includes an elastic fabric base, conductive fibers and fabric fibers, the elastic fabric base includes several latex threads, and the conductive fibers are reciprocally woven on several latex threads to form a Reticular structure, the winding joints of the conductive fibers and the latex filaments are bound and fixed by fabric fibers so that the conductive fibers and the latex filaments are limited and fixed, and the two adjacent conductive fibers are in contact with each other under the pull of the latex filaments or Separation to cause a change in resistance enables the measurement of strain. The braided strain sensor has the characteristics of wide measurement range and high sensitivity, and can measure a full range of human body motion signals, such as pulse beating, muscle motion, and motion at human joints; it has stable performance and good repeatability, after 3000 cycles Loading, there is no obvious difference in signal; the braided strain sensor can be washed; adopting traditional weaving process, mass production can be realized.

Description

A high-sensitivity braided strain sensor and its preparation method

technical field

The invention relates to the technical field of fabric strain sensors, in particular to a high-sensitivity woven strain sensor and a preparation method thereof.

Background technique

In recent years, the emergence and development of flexible electronic technology has attracted worldwide attention. Among them, flexible large-strain sensors, as an important branch of flexible electronic devices, have important application value in smart wear, medical rehabilitation, and intelligent robots.

At present, a common flexible large-strain sensor is a composite structure of a flexible polymer substrate (such as PDMS, etc.) and micro-nano conductive materials (such as carbon nanotubes, silver nanowires, graphene oxide, etc.). This strain sensor can achieve high sensitivity (GF>100) and large measurement range (strain 100% or even higher), but this strain sensor has some disadvantages: poor air permeability, poor heat dissipation, poor comfort due to long-term contact with the human body, etc. . The braided strain sensor has better comfort and is easier to integrate with clothing, which is more conducive to its application in smart clothing. However, the current braided strain sensor has disadvantages such as low sensitivity, small measurement range, poor stability, and non-washable due to the preparation process.

Therefore, in order to solve the above problems, a high-sensitivity braided strain sensor is now designed.

Contents of the invention

The purpose of the present invention is to provide a high-sensitivity braided strain sensor and its preparation method to solve the problems of poor air permeability, poor heat dissipation, poor comfort caused by long-term contact with the human body, low sensitivity and small measurement range of similar fabric strain sensors in the prior art. technical problem.

In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

A high-sensitivity braided strain sensor, comprising an elastic fabric base, conductive fibers and fabric fibers, the elastic fabric base includes several latex threads, the conductive fibers are reciprocally woven on several latex threads and form a mesh structure, The connection between the conductive fiber and the latex wire is bound and fixed by fabric fibers so that the conductive fiber and the latex wire are limited and fixed, and the two adjacent conductive fibers are pulled by the latex wire to contact or move away from each other to cause a change in resistance To realize the perception and measurement of strain.

As a preferred solution of the present invention, several latex filaments are arranged parallel to each other.

As a preferred solution of the present invention, the conductive fiber is reciprocally woven with several latex filaments to form a grid-like structure.

As a preferred solution of the present invention, the conductive fibers are woven on the pre-strained latex filaments.

As a preferred solution of the present invention, after the conductive fibers are braided with the pre-strained latex filaments, the common fabric fibers are used to bind the conductive fibers and the latex filaments together at the junction to avoid The relative slippage between the wire fibers and the latex filaments.

As a preferred solution of the present invention, after weaving, the pre-strain of the latex filaments is released, so that the conductive fibers are in contact with each other.

As a preferred solution of the present invention, the conductive fiber can be selected from any of the following conductive materials but not limited to: silver limiter, copper fiber, carbon fiber, gold fiber.

As a preferred solution of the present invention, the fabric fiber is made of any one of the following materials, but not limited to: polyester filaments, nylon filaments, polypropylene filaments.

As a preferred solution of the present invention, the sensor has a measurable strain of more than 50%, and a strain sensitivity coefficient of 100 or even higher.

As a preferred version of the present invention, the preparation method comprises:

S1: Stretch multiple latex filaments arranged in parallel to the limit of their own elasticity;

S2: Weaving a strand of conductive fiber back and forth on the latex filament to form a network structure;

S3: Bind the junction of the wire fiber and the latex wire with the fabric fiber by knitting, so that the wire fiber is limited and fixed on the latex wire;

S4: The pre-strain of the overall structure is released, and the network structure formed between the conductive fibers and latex filaments shrinks, causing two adjacent conductive fibers to contact each other.

In order to solve the above technical problems, the present invention further provides the following technical solutions:

Compared with the prior art, the present invention has the following beneficial effects:

Compared with a large strain sensor with a polymer substrate, the strain sensor of the present invention has good air permeability, good heat dissipation, good comfort and is easier to integrate with clothing, which is beneficial to the application of the strain sensor in smart clothing. Compared with the existing braided strain sensor, the braided strain sensor of the present invention has high sensitivity (the sensitivity factor GF can reach 100 or even higher), and can measure a full range of human body motion signals, such as pulse beating, muscle motion and human body joints Stable performance, good repeatability, no significant difference in signal after 3000 cycles of loading; the braided strain sensor can be washed; using traditional weaving technology, mass production can be achieved; wide measurement range (measurable strain range more than 50%), it can measure large motion deformation of human joints; stable performance and good repeatability, after 3000 cycles of loading, there is no significant difference in signal; the woven strain sensor can be washed; using traditional weaving technology, it can realize Mass production.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that are required in the description of the embodiments or the prior art. Apparently, the drawings in the following description are only exemplary, and those skilled in the art can also obtain other implementation drawings according to the provided drawings without creative work.

The structures, proportions, sizes, etc. shown in this manual are only used to cooperate with the content disclosed in the manual, so that people familiar with this technology can understand and read, and are not used to limit the conditions for the implementation of the present invention, so there is no technical In the substantive meaning above, any modification of structure, change of proportional relationship or adjustment of size shall still fall within the scope of the technical content disclosed in the present invention without affecting the functions and objectives of the present invention. within the range that can be covered.

Fig. 1 is the schematic diagram of braided strain sensor provided by the present invention;

Fig. 2 is that the strain sensor resistance of different size silver fiber weaving provided by the present invention changes with strain;

Fig. 3 is the variation of strain sensor resistance with strain of different widths provided by the present invention;

Figure 4 shows the resistance change of the braided strain sensor provided by the present invention after repeated loading and unloading for 3000 times (under 50% strain condition);

Fig. 5 is the physical figure of the braided strain sensor provided by the present invention;

The labels in the figure are respectively indicated as follows:

1. Latex silk; 2. Conductive fiber; 3. Fabric fiber.

Detailed ways

The implementation mode of the present invention is illustrated by specific specific examples below, and those who are familiar with this technology can easily understand other advantages and effects of the present invention from the contents disclosed in this description. Obviously, the described embodiments are a part of the present invention. , but not all examples. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figures 1 and 5, the present invention provides a high-sensitivity braided strain sensor, comprising an elastic fabric base, conductive fibers 2 and fabric fibers 3, the elastic fabric base includes several latex filaments 1, and the conductive fibers 2 are reciprocally woven in Several latex threads 1 are placed on and form a network structure, and the intersection of conductive fibers 2 and latex threads 1 is bound and fixed by fabric fibers 3 so that the space between conductive fibers 2 and latex threads 1 is limited and fixed, and two adjacent strands of conductive fibers 2 Under the pull of the latex wire 1, they contact or separate from each other to cause a change in resistance to measure the strain.

When the braided strain sensor is stretched and deformed, the conductive fibers in contact with each other will separate, resulting in a change in the resistance of the overall structure, so that the strain is converted into an electrical signal, and the strain of the measured object can be obtained by measuring the change in the resistance of the structure. The strain sensor invented has good air permeability, good heat dissipation, good comfort and is easier to integrate with clothing, which is conducive to the application of strain sensors in smart clothing.

In order to ensure that the springback between the latex filaments is carried out along a parallel direction, the conductive fibers wound thereon can be attached and contacted with each other.

As shown in Fig. 1 and Fig. 5, several latex threads 1 are arranged parallel to each other.

Further, as shown in Figure 1 and Figure 5, the conductive fiber 2 and several latex threads 1 are reciprocally woven to form a cross-shaped network structure, which facilitates the elastic connection between the conductive fiber 2 and the latex thread 1, and makes the conductive fiber 2 and the latex thread 1 reciprocally woven. A complete loop is formed between bit 2 and latex wire 1, which in turn facilitates the resistance change in the strain sensor.

Further, as shown in Fig. 1 and Fig. 5, the conductive fiber 2 is woven on the pre-strained latex filament 1, and after the conductive fiber 2 is woven on the pre-strained latex filament 1, the conductive fiber 3 is woven with the common fabric fiber 3. 2 and latex wire 1 are bundled together at the junction to avoid relative slippage between the conductor fiber 2 and the latex wire 1, so that two adjacent strands of conductive fiber 2 can move in parallel directions under the pull of the latex wire 1 , so as to facilitate the lamination of two adjacent conductive fibers 2, which can largely avoid the relaxation of the strain sensor.

Specifically, as shown in Figure 3, the sensor has a measurable strain of more than 50% and a strain sensitivity of 100-1160, and can measure a full range of human motion signals, such as pulse beating, muscle motion, and motion at human joints, etc. ; The performance is stable and the repeatability is good. After 3000 cycles of loading, there is no obvious difference in the signal (as shown in Figure 4).

Preparation methods include:

S1: Stretch a plurality of latex filaments 1 arranged in parallel to the limit of its own elasticity;

S2: reciprocally weaving a strand of conductive fiber 2 onto the latex filament 1 to form a network structure;

S3: Bind the joint of the wire fiber 2 and the latex wire 1 with the fabric fiber 3 by knitting, so that the wire fiber 2 is limitedly fixed on the latex wire 1;

S4: The pre-strain of the overall structure is released, and the network structure formed between the conductive fiber 2 and the latex filament 1 shrinks, causing two adjacent conductive fibers to contact each other.

Embodiment one

As shown in Figure 5, 7 latex wires are placed in parallel, the distance between the latex wires is 1.4 mm, the diameter of the latex wires is 0.5 mm, and the latex wires are stretched to the elastic limit (about 130%). The conductive fiber adopts 210D (D: the measurement unit of Denier fiber size) silver fiber (each silver fiber contains 24), the conductive fiber is reciprocally woven onto the pre-stretched latex wire, and at the same time, the 150D spandex wire is used for similar knitting. Methods The silver fiber and latex wire are tightly bound together, and the pre-strain of the overall structure is released after weaving to form a braided strain sensor. The gage factor (GF) of the strain sensor can reach 100, and the strain measurement range can reach 50%.

The conductive fiber in this embodiment can use other conductive materials according to different requirements, such as: silver fiber, copper fiber, carbon fiber, gold fiber, etc.; the fabric fiber can also use other materials, such as: polyester silk, nylon silk, polypropylene silk, etc. .

Embodiment two

As shown in Figure 5, 7 latex wires are placed in parallel, the distance between the latex wires is 1.4 mm, the diameter of the latex wires is 0.5 mm, and the latex wires are stretched to the elastic limit (about 130%). The conductive fiber adopts 70D (D: the measurement unit of Denier fiber size) silver fiber (each silver fiber contains 8 pieces), and the conductive fiber is reciprocally woven onto the pre-stretched latex filament, and at the same time, the 150D spandex filament is used to knit similarly. Methods The silver fiber and latex wire are tightly bound together, and the pre-strain of the overall structure is released after weaving to form a braided strain sensor. The gage factor (GF) of the strain sensor can reach 50, and the strain measurement range can reach 100%.

The conductive fiber in this embodiment can use other conductive materials according to different requirements, such as: silver fiber, copper fiber, carbon fiber, gold fiber, etc.; the fabric fiber can also use other materials, such as: polyester silk, nylon silk, polypropylene silk, etc. .

Embodiment three

As shown in Figure 5, 7 latex wires are placed in parallel, the distance between the latex wires is 1.4 mm, the diameter of the latex wires is 0.5 mm, and the latex wires are stretched to the elastic limit (about 130%). The conductive fiber adopts 140D (D: the measurement unit of Denier fiber size) silver fiber (each silver fiber contains 16 pieces), and the conductive fiber is reciprocally woven onto the pre-stretched latex filament, and at the same time, the 150D spandex filament is used to knit similarly. Methods The silver fiber and latex wire were tightly bound together, and the pre-strain of the overall structure was released after weaving to form a braided strain sensor. The gage factor (GF) of the strain sensor can reach 100, and the strain measurement range can reach 60%.

Embodiment four

As shown in Figure 5, 25 latex filaments are placed in parallel, the distance between the latex filaments is 1.4mm, the diameter of the latex filaments is 0.5mm, and the latex filaments are stretched to the elastic limit (about 130%). The conductive fiber adopts 240D (D: the measurement unit of Denier fiber size) silver fiber (each silver fiber contains 24), the conductive fiber is reciprocally woven onto the pre-stretched latex wire, and at the same time, the 150D spandex wire is used to knit similarly. Methods The silver fiber and latex wire are tightly bound together, and the pre-strain of the overall structure is released after weaving to form a braided strain sensor. The gage factor (GF) of the strain sensor can reach 1160, and the strain measurement range can reach 50%.

The conductive fiber in this embodiment can use other conductive materials according to different requirements, such as: silver fiber, copper fiber, carbon fiber, gold fiber, etc.; the fabric fiber can also use other materials, such as: polyester silk, nylon silk, polypropylene silk, etc. .

As shown in Figure 2, it is shown that the size of the conductive fiber affects the sensitivity coefficient and the strain measurement range of the strain sensor through Embodiment 1, Embodiment 2 and Embodiment 3. The specific relationship is that the larger the size of the conductive fiber, the greater the strain sensor's The sensitivity factor will also increase accordingly; the larger the size of the conductive fiber, the smaller the strain measurement range of the strain sensor will be. In addition, as shown in Figure 3, through the comparison of the sensor widths of Embodiment 1 and Embodiment 4, when other parameters remain unchanged, the wider the braided strain sensor, the higher its sensitivity.

The above embodiments are only exemplary embodiments of the present application, and are not intended to limit the present application, and the protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent replacements to the present application within the spirit and protection scope of the present application, and such modifications or equivalent replacements shall also be deemed to fall within the protection scope of the present application.

Claims (10)

1. A high-sensitivity braided strain sensor, characterized in that it includes an elastic fabric base, conductive fibers (2) and fabric fibers (3), the elastic fabric base includes several latex filaments (1), and the conductive fibers ( 2) Reciprocating weaving on several latex filaments (1) to form a network structure, the intersection of the conductive fibers (2) and the latex filaments (1) is bound and fixed by fabric fibers (3) so that the conductive fibers ( 2) The limit is fixed with the latex wire (1), and the two adjacent strands of conductive fibers (2) contact or separate from each other under the pull of the latex wire (1) to cause a change in resistance to measure the strain. 2. A high-sensitivity braided strain sensor according to claim 1, characterized in that several latex threads (1) are arranged parallel to each other. 3 . The high-sensitivity braided strain sensor according to claim 1 , characterized in that: the conductive fiber ( 2 ) is reciprocally woven with several latex threads ( 1 ) to form a grid-like structure. 4 . 4. A high-sensitivity braided strain sensor according to claim 3, characterized in that: the conductive fiber (2) is braided on the pre-strained latex wire (1). 5. A high-sensitivity braided strain sensor according to claim 4, characterized in that: after the conductive fiber (2) is braided on the pre-strained latex wire (1), the ordinary fabric fiber (3 ) Bundling the conductive fibers (2) and the latex filaments (1) together at junctions to avoid relative slippage between the conductive fibers (2) and the latex filaments (1). 6 . The high-sensitivity braided strain sensor according to claim 5 , characterized in that: after weaving, the pre-strain of the latex filaments ( 1 ) is released, so that the conductive fibers ( 2 ) are in contact with each other. 7. A high-sensitivity braided strain sensor according to claim 1, characterized in that: the conductive fiber (2) can choose any of the following conductive materials but not limited to the following conductive materials: silver fiber, copper fiber, Carbon fiber, gold fiber. 8. A high-sensitivity braided strain sensor according to claim 1, characterized in that: the fabric fiber (3) is made of any of the following materials but not limited to: polyester yarn, nylon yarn, polypropylene fiber Silk. 9. A high-sensitivity braided strain sensor according to claim 1, characterized in that: the sensor has a strain measurement range of more than 50% and a strain gage factor of more than 100. 10. The preparation method of a high-sensitivity braided strain sensor according to any one of claims 1-6, characterized in that: the preparation method comprises: S1: Stretch multiple latex filaments (1) arranged in parallel to the limit of their own elasticity; S2: reciprocally weaving a strand of conductive fiber (2) onto the latex filament (1) to form a network structure; S3: Bind the junction of the conductive fiber (2) and the latex thread (1) with the fabric fiber (3) by knitting, so that the conductive fiber (2) is limitedly fixed on the latex thread (1); S4: The pre-strain of the overall structure is released, and the network structure formed between the conductive fibers (2) and the latex filaments (1) shrinks, causing two adjacent strands of conductive fibers to contact each other.

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